回复: Bug in dash: Incorrect behaviour of $LINENO in function

["anonymous4feedback@xxxxxxxxxxx" <anonymous4feedback@xxxxxxxxxxx>]

Sorry I didn't explain this clearly, and I made some wrong assumption in the first email.

I made another simpler test

# line 1 is empty
# line 2 is empty
foo(){ # line 2
  echo $LINENO; } # line 3
foo # line 4

dash prints 2, (line number in function, counting from 1)
bash and ksh prints 4, (line number in whole script)
and zsh prints 1 (line number in function, counting from 0)

More test moving the lines around confirms the guess in parens.

Can I say that none of these is wrong because there is no standard about this?


发件人: Marc Chantreux <mc@xxxxxxxxxx>
发送时间: 2023年1月14日 17:39
收件人: anonymous4feedback@xxxxxxxxxxx <anonymous4feedback@xxxxxxxxxxx>
抄送: dash@xxxxxxxxxxxxxxx <dash@xxxxxxxxxxxxxxx>
主题: Re: Bug in dash: Incorrect behaviour of $LINENO in function 
 
hello,

> It seems dash stores the line number of the parameter substitution and the line number of the function definition

which is what we expect from a variable expansion. what you need here
is an alias because it works like a minimal but dynamic preprocessor

those are the tricks about aliases:

* they really act as a preprocessor so

        alias warn='>&2 echo here at $LINENO'
        f() warn first
        alias warn='>&2 echo another message at $LINENO'
        g() warn last
        f;g

        # does

        here at 1 first
        another message at 1 last

* interpolation comes first so 

        entering() {
                echo entering "$@"
                "$@"
        }
        f() echo doing things in functions
        alias damn='echo oops ...'
        entering f
        entering damn

        entering f
        doing things in functions
        entering damn
        /home/mc/src/vendor/dash/src/dash: 3: damn: not found

conclusion:

* use functions as long as you can
* in this case, you can't. your solution is

        alias warn='>&2 echo here at $LINENO'

HTH,
Marc Chantreux